Catalytic supports with controlled pore properties

ABSTRACT

A catalyst support suitable for use in a cracking process or hydrotreating process. The catalyst support comprises a magnesia-alumina-aluminum phosphate matrix which has outstanding thermal stability.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention resides in catalytic supports. Particularly, theinvention teaches catalytic supports which can be combined with metalssuitable for use in either a fluid cracking process or a hydrotreatingprocess.

The catalyst supports herein, when formulated with the requisite metals,are particularly formulated to increase the gasoline yield and quality(i.e., BTX) from gas oils during a cracking process and additionally tocatalytically crack petroleum residuals with high selectivity togasoline production as well as having improved metals tolerancecharacteristics. Examples of typical metals which can be present duringthe cracking and/or hydrotreating process include: nickel, vanadium,copper, chromium, iron, cobalt, molybdenum, and inorganic oxides such asthe zeolites, etc.

2. Description of the Prior Art

In my U.S. Pat. No. 4,210,560, dated July 1, 1980, I discovered acatalyst support which can be utilized in a fluid catalyst crackingprocess or a hydrotreating process, depending upon the type metalsformulated with the support, comprising a magnesia-alumina-aluminumphosphate matrix characterized after calcination at 500° C. for 10 hoursas amorphous and having an average pore radius of from about 10 A toabout 300 A, preferably from about 75 A to about 200 A; a surface arearanging from about 100 m² /g to about 350 m² /g, especially from about125 m² /g to about 250 m² /g; a pore volume of from about 0.3 cc/g toabout 1.5 cc/g, preferably from about 0.7 cc/g to about 1.2 cc/g;wherein the magnesia-alumina-aluminum phosphate matrix has a molepercent ratio of from about 10:80:10 to about 25:10:65, especially fromabout 10:55:35 to about 20:35:45, and wherein said matrix retains atleast 90 percent of its surface area when the matrix is additionallycalcined at a temperature up to about 750° C. for about 10 hours.

SUMMARY OF THE INVENTION

I have also discovered that catalyst supports similar to those definedand claimed in my U.S. Pat. No. 4,210,560, but wherein the molar ratiosof magnesia, alumina and aluminum phosphate are outside the molar ratioranges defined and claimed in said U.S. Pat. No. 4,210,560, will alsohave properties similar thereto. Accordingly, the invention defined andclaimed herein resides in a catalyst support comprising amagnesia-alumina-aluminum phosphate matrix characterized aftercalcination at 500° C. for about 10 hours as amorphous, and having anaverage pore radius of from about 10 A to about 300 A, preferably fromabout 75 A to about 200 A; a surface area ranging from about 100 m² /gto about 350 m² /g, especially from about 125 m² /g to about 250 m² /g;a pore volume of from about 0.3 cc/g to about 1.5 cc/g, preferably fromabout 0.7 cc/g to about 1.2 cc/g; wherein the magnesia-alumina-aluminumphosphate matrix contains magnesia in an amount ranging from about 10 toabout 25 mole percent, preferably from about 12 to about 20 molepercent, alumina in an amount ranging from about two to about 85 molepercent, preferably about eight to about 80 mole percent, and aluminumphosphate in an amount ranging from at least about three mole percentbut less than about 10 mole percent, preferably about five to about ninemole percent, or in the range above about 65 to about 85 mole percent,preferably about 70 to about 80 mole percent, and wherein said matrixretains at least about 90 percent of its surface area when the matrix isadditionally calcined at a temperature up to about 750° C. for about 10hours.

DESCRIPTION OF THE INVENTION

As pointed out above, the present invention resides in catalyticsupports. The supports herein can conveniently be used in fluid catalystcracking processes and hydrotreating processes. One such process is setforth in U.S. Pat. No. 4,179,358, dated Dec. 18, 1979 of Swift et al.,the disclosure of which is incorporated herein by reference.

The catalyst support herein is a magnesia-alumina-aluminum phosphatematrix of the formula:

    MgOAl.sub.2 O.sub.3 AlPO.sub.4,

wherein the magnesia is present in an amount ranging from about 10 toabout 25 mole percent, preferably from about 12 to about 20 molepercent, alumina in an amount ranging from about two to about 85 molepercent, preferably about eight to about 80 mole percent, and aluminumphosphate in an amount ranging from at least about three mole percentbut less than about 10 mole percent, preferably about five to about ninemole percent, or in the range above about 65 mole percent to about 85mole percent, preferably about 70 to about 80 mole percent.

It is to be noted that the magnesia-alumina-aluminum phosphate matrixherein is characterized after calcination at 500° C. for about 10 hours,as amorphous and having an average pore radius of from about 10 A toabout 300 A, preferably from about 75 A to about 200 A; a surface arearanging from about 100 m² /g to about 350 m² /g, preferably from about125 m² /g to about 250 m² /g; and a pore volume of from about 0.3 cc/gto about 1.5 cc/g, preferably from about 0.7 cc/g to about 1.2 cc/g; andwherein said matrix retains at least 90 percent of its surface area whenthe matrix is additionally calcined at a temperature up to about 750° C.for about 10 hours.

The magnesia-alumina-aluminum phosphate catalyst supports herein can beconveniently prepared by admixing together an aqueous solution ofaluminum nitrate with an aqueous solution of magnesium nitrate and 85percent aqueous phosphoric acid. The magnesia-alumina-aluminum phosphatecatalyst support can be conveniently precipitated from solution by theaddition of ammonium hydroxide. Normally, the solution pH is maintainedat or about 9.0, however, the pH can be initially lower than 9.0 andslowly raised to pH 9.0 as the reaction proceeds. It should be notedthat the pore size of the catalyst support can be controlled by varyingthe pH of the solution. In preparing the novel magnesia-alumina-aluminumphosphate support herein magnesium nitrate, aluminum nitrate andphosphoric acid are used in molar amounts stoichiometricallycorresponding to the amounts of magnesium, aluminum and phosphatecomponents in the desired support.

The aluminum nitrate herein can conveniently be prepared by addingnitric acid to aluminum and crystalizing the resultant aluminum nitratefrom solutions. Similarly, magnesium nitrate can be prepared by addingnitric acid to magnesium oxide and crystalizing the resultant magnesiumnitrate from solution.

After the magnesia-alumina-aluminum phosphate matrix is filtered fromsolution it is dried at about 120° C. and calcined at about 500° C. forabout 10 hours using conventional apparatus. The matrix was examinedafter calcination and was found to be amorphous.

It is to be noted that the catalyst supports herein can conveniently beadmixed with zeolites to produce cracking catalysts which provide for animproved process for increasing gasoline yield and quality of eitherlight or heavy feedstocks which can additionally contain a high metalscontent.

Typical zeolites or molecular sieves having cracking activity and whichcan be suitably dispersed in a matrix for use as a catalytic crackingcatalyst are well known in the art. Suitable zeolites are described, forexample, in U.S. Pat. No. 3,660,274 to James J. Blazek et al. Thedescription of the crystalline aluminosilicates in the Blazek et alpatent is incorporated herein by reference. Synthetically preparedzeolites are initially in the form of alkali metal aluminosilicates. Thealkali metal ions are exchanged with rare earth metal ions to impartcracking characteristics to the zeolites. The zeolites are, of course,crystalline, three-dimensional, stable structures containing a largenumber of uniform openings or cavities interconnected by smaller,relatively uniform holes or channels. The effective pore size ofsynthetic zeolites is suitably between 6 A and 15 A in diameter. Theoverall formula for the zeolites can be represented as follows:

    xM.sub.2 /.sub.n O:Al.sub.2 O.sub.3 :1.5-6.5SiO.sub.2 :yH.sub.2 O

where M is a metal cation and n its valence and x varies from 0 to 1 andy is a function of the degree of dehydration and varies from 0 to 9, Mis preferably a rare earth metal cation such as lanthanum, cerium,praseodymium, neodymium, etc., or mixtures of these.

Zeolites which can be employed in combination with this inventioninclude both natural and synthetic zeolites. These zeolites includegmelinite, chabazite, dachiardite, clinoptilolite, faujasite,heulandite, analcite, levynite, erionite, sodalite, cancrinite,nepheline, lazurite, scolecite, natrolite, offretite, mesolite,mordenite, brewsterite, ferrierite, and the like. The faujasites arepreferred. Suitable synthetic zeolites which can be treated inaccordance with this invention include zeolites X, Y, A, L, ZK-4, B, E,F, HJ, M, Q, T, W, Z, alpha and beta, ZSM-types and omega. The term"zeolites" as used herein contemplates not only aluminosilicates butsubstances in which the aluminum is replaced by gallium and substancesin which the silicon is replaced by germanium.

The preferred zeolites for use in combination with this invention arethe synthetic faujasites of the types Y and X or mixtures thereof;however, the Y-type zeolites are superior when used herein.

It is to be noted that some X-type zeolite will be mixed with the Y-typezeolite due to the difficulty and cost involved in separating the twozeolites. It is additionally noted that the presence of small amounts ofthe X-type zeolite will not substantially impair the superiorselectivity to gasoline production of the catalysts herein.

It is also well known in the art that to obtain good cracking activitythe zeolites have to be in a proper form. In most cases this involvesreducing the alkali metal content of the zeolite to as low a level aspossible. Further, a high alkali metal content reduces the thermalstructural stability, and the effective lifetime of the catalyst will beimpaired as a consequence thereof. Procedures for removing alkali metalsand putting the zeolites in the proper form are well known in the art asdescribed in U.S. Pat. No. 3,537,816.

The crystalline aluminosilicate zeolites, such as synthetic faujasite,will under normal conditions, crystallize as regularly shaped, discreteparticles of approximately one to ten microns in size, and, accordingly,this is the size range normally used in commercial catalysts. Preferablythe particle size of the zeolites is from 0.5 to 10 microns and morepreferably is from 1 to 2 microns or less. Crystalline zeolites exhibitboth an interior and an exterior surface area, with the largest portionof the total surface area being internal. Blockage of the internalchannels by, for example, coke formation and contamination by metalspoisoning will greatly reduce the total surface area. Therefore, tominimize the effect of contamination and pore blockage, crystals largerthan the normal size cited above are preferably not used in thecatalysts of this invention.

The term REY-zeolites as defined herein is the Y-type zeolite that hasundergone an ion exchange reaction with rare earth metal ions. Thenaturally occurring molecular sieve zeolites are usually found in thesodium form, an alkaline earth metal form, or mixed forms. The syntheticmolecular sieves are normally in their sodium form, however. it shouldbe understood that other alkali metal compounds can be substitutedtherefor. In their sodium form, the Y zeolites suitable for use hereincorrespond to the general formula:

    0.9±0.2NaO:Al.sub.2 O.sub.3 :nSiO.sub.2 :xH.sub.2 O

wherein n is an integer of from about 3 to about 6 and x is an integerof from about 0 to about 9. It is to be noted that after the ionexchange reaction with the rare earth metals, the sodium content of theY zeolite is from about 0.3 to about 1 molar percent, especially fromabout 0.5 to about 0.8 molar percent. When sodium is present above thismolar range, it tends to deactivate the catalyst and to reduce thesodium content below 0.3 molar percent is too expensive to justify.

Rare earth metals can conveniently be substituted for the sodium in theY zeolite above using conventional techniques and methods. A widevariety of rare earth compounds can be ion exchanged with the abovesodium ions. Operable compounds include rare earth chlorides, bromides,iodides, carbonates, bicarbonates, sulfates, sulfides, thiocyanates,peroxysulfates, acetates, benzoyates, citrates, fluorides, nitrates,formates, propionates, butyrates, valecates, lactates, malanates,oxalates, palmitates, hydroxides, tartrates and the like. The preferredrare earth salts are the chlorides, nitrates and sulfates. It is to benoted that the only limitation on the particular rare earth metal saltor salts employed is that it be sufficiently soluble in the ion exchangefluid medium in which it is used to give the necessary rare earth iontransfer.

Representative of the rare earth metals are cerium, lanthanum,praseodymium, neodymium, illinium, samarium, europium, gadolinium,terbium, dysprosium, holmium, erbium, thulium, scandium, yttrium, andlutecium.

The rare earth metal salts employed can either be the salt of a singlerare earth metal or mixtures of rare earth metals, such as rare earthchlorides of didymium chloride. As hereinafter referred to, unlessotherwise indicated, a rare earth chloride solution is a mixture of rareearth chlorides consisting essentially of the chlorides of lanthanum,cerium, neodymium and praseodymium with minor amounts of samarium,gadolinium, and yttrium. Rare earth chloride solutions are commerciallyavailable and the ones specifically referred to in the examples containthe chlorides of the rare earth mixture having the relative compositioncerium (as CeO₂) 48 percent by weight, lanthanum (as La₂ O₃) 24 percentby weight, praseodymium (as Pr₆ O₁₁) 5 percent by weight, neodymium (asNd₂ O₃) 17 percent by weight, samarium (as Sm₂ O₃) 3 percent by weight,gadolinium (as Gd₂ O₃) 2 percent by weight, and other rare earth oxides0.8 percent by weight. Didymium chloride is also a mixture of rare earthchlorides but having a lower cerium content. It consists of thefollowing rare earth determined as oxides: lanthanum 45-56 percent byweight, cerium 1-2 percent by weight, praseodymium 9-10 percent byweight, neodymium 32-33 percent by weight, samarium 5-7 percent byweight, gadolinium 3-4 percent by weight, yttrium 0.4 percent by weight,and other rare earths 1-2 percent by weight. It is to be understood thatother mixtures of rare earths are also applicable for use in combinationwith the catalytic supports of this invention, although lanthanum,neodymium, praseodymium, samarium and gadolinium as well as mixtures ofrare earth cations containing a predominant amount of one or more of theabove cations are preferred since these metals provide optimum activityfor hydrocarbon conversion, including catalytic cracking.

It should be noted that the zeolites when admixed with the catalystsupports herein are normally composited therewith from about 5 to about50 weight percent, preferably from about 5 to about 35 weight percentbased on the weight of said catalyst support.

The matrix or catalyst support herein can additionally be used incombination with metals normally used in a hydrotreating process, forexample, in a desulfurization and/or denitrogenation process.

DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE I

A catalyst support comprising a magnesia-alumina-aluminum phosphatematrix was prepared according to the following procedure.

A first solution was prepared by dissolving 356.25 grams of aluminumnitrate in 2 liters of distilled water. A second solution was preparedby dissolving 38.46 grams of magnesium nitrate in 1 liter of distilledwater. The two solutions must be clear. Next, the two solutions werecombined and 85.76 grams of 85 percent phosphoric acid were added andthe resulting mixture was agitated for about 5 minutes in a mixingvessel equipped with an electric stirrer. Approximately 2 liters ofdistilled water was prepared to provide a stirring medium. A stocksolution of ammonium hydroxide was diluted with distilled water (ratio=1:1) was prepared. The stock solution of ammonium hydroxide andpreviously mixed solution were slowly added from separate burets to amixing vessel containing the stirring medium electric stirrer and pHelectrodes. The solution pH of the stirring medium was maintained at 9.0by adjusting the flow rates of the two burets. Vigorous stirring wasmaintained throughout the mixing period. A white precipitate formedwhich was recovered from solution by filtration. The filter cake, thusrecovered, was washed with 8 liters of distilled water and dried in anelectrically heated oven at 120° C. Next the filter cake was calcined inheated air at 500° C. for 10 hours. The pore properties of the calcinedsample were measured by a standard nitrogen adsorption procedure basedon the Brunauer, Emmett and Teller method, as modified by Barrett, E.P., Joyner, L. G. and Halenda, P. P., J.A.C.S. 63, P. 373 (1951). Theresults are shown in Table I.

EXAMPLE II

The procedure of Example I was followed to produce amagnesia-alumina-aluminum phosphate catalyst support, but with thefollowing exceptions: used were 607.5 grams of aluminum nitrate, 9.14grams of 85 percent phosphoric acid and 38.46 grams of magnesiumnitrate. The results obtained are set forth below in Table I.

                  TABLE I                                                         ______________________________________                                        VARIATION OF PORE CHARACTERISTICS WITH                                        COMPOSITION OF SAMPLES PREPARED AT THE SAME                                   CONSTANT pH, CALCINATION TEMPERATURE: 500° C.                          Example No.         I       II                                                ______________________________________                                        R.P. (A)            157.0   59.1                                              Pore Volume (cc/g)  0.51    0.64                                              Av. Pore Radius (A) 79.0    38.3                                              Surface Area (m.sup.2 /g)                                                                         130.1   333.1                                             Pore Size Distribution                                                        (Volume Percent)                                                              200-300 A radius    30.6    3.1                                               100-200             43.2    13.1                                              50-100              16.9    43.0                                              40-50               2.1     10.3                                              30-40               2.8     10.0                                              20-30               2.6     10.0                                              <20                 2.0     10.7                                              Stoichiometry, Mole Percent                                                   MgO                 15      15                                                Al.sub.2 O.sub.3    10      77                                                AlPO.sub.4          75      8                                                 ______________________________________                                    

EXAMPLE III

A representative REY-zeolite catalyst can be prepared according to thefollowing procedure:

Into a 4-liter, 3-necked flask equipped with a mechanical stirrer, awater-cooled condenser and thermometer are added 2400 ml. of waterheated to 80° C., with stirring. To the water are added 800 grams ofsodium Y zeolite and 564 grams rare earth chloride mixture comprising 48percent cerium, 24 percent lanthanum, 5 percent praseodymium, 17 percentneodymium, 3 percent samarium, 2 percent gadolinium and 0.8 percentother rare earth compounds. It is to be noted that all percents are byweight. The temperature will be maintained at 80° C. for two hours withcontinued stirring and the reaction mixture then filtered. The filteredREY-zeolite can then be reslurried with 2400 ml of water and heated to atemperature of 80° C. Next, an additional 564 grams of the above rareearth chloride mixture are added to the solution. The temperature isthen maintained at 80° C. for two hours with stirring. The resultingREY-zeolite is filtered and washed with eight 1-liter batches of water.

The REY-zeolite is calcined at 538° C. for 10 hours, slurried with 2400ml. of water and heated to 80° C. The procedure set forth above for theaddition of the rare earth chloride mixture to the Y-type zeolite can berepeated two additional times and the final reaction product filteredand washed with eight 1-liter batches of water.

Next, the matrix produced in Example I can then be slurried and added tothe REY-zeolite produced above. The slurry is then spray dried andcalcined for 10 hours at 500° C. to produce the desired catalyst. It isto be noted that the REY-zeolite content of the catalyst can be variedaccording to the wishes of the formulator, however, a weight percent offrom about 5 percent to about 35 percent based on the total catalystweight is desirable, especially 15 weight percent.

Obviously, many modifications and variations of the invention, ashereinabove set forth, can be made without departing from the spirit andscope thereof, and therefore only such limitations should be imposed asare indicated in the appended claims.

I claim:
 1. A catalyst support consisting essentially of amagnesia-alumina-aluminum phosphate matrix characterized aftercalcination at 500° C. for 10 hours as amorphous, and having an averagepore radius of from about 10 A to about 300 A, a surface area rangingfrom 100 m² /g to about 350 m² /g, a pore volume of from about 0.3 cc/gto about 1.5 cc/g, wherein the magnesia-alumina-aluminum phosphatematrix contains magnesia in an amount ranging from about 10 to about 25mole percent, alumina in an amount ranging from about two to about 85mole percent, and aluminum phosphate in an amount ranging from at leastabout three mole percent but less than about 10 mole percent, or in therange above about 65 mole percent to about 85 mole percent, and whereinsaid matrix retains at least about 90 percent of its surface area whenthe matrix is additionally calcined at a temperature up to about 750° C.for about 10 hours.
 2. The catalyst support of claim 1 wherein themagnesia is present in a mole percent range of about 12 to about 20, thealumina in a mole percent range of about eight to about 80 and thealuminum phosphate in a mole percent range of about five to about nine,or about 70 to about
 80. 3. The catalyst support of claim 1 wherein theaverage pore radius is in the range of about 75 to about 200 A.
 4. Thecatalyst support of claim 1 wherein the surface area is in the range ofabout 125 to about 250 m² /g.
 5. The catalyst support of claim 1 whereinthe pore volume is in the range of about 0.7 to about 1.2 cc/g.